{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:gnu:glibc:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "2.34"
              },
              {
                "last_affected": "2.43"
              }
            ],
            "source": "CPE_RANGE"
          },
          "events": [
            {
              "introduced": "ae37d06c7d127817ba43850f0f898b793d42aea7"
            },
            {
              "last_affected": "f762ccf84f122d1354f103a151cba8bde797d521"
            }
          ],
          "repo": "https://sourceware.org/git/glibc.git",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "glibc",
    "cwe_ids": [
      "CWE-20"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4438.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "2.34"
          },
          {
            "last_affected": "2.43"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C library version 2.34 to version 2.43 could result in an invalid DNS hostname being returned to the caller in violation of the DNS specification.",
  "id": "CVE-2026-4438",
  "modified": "2026-07-08T05:37:47.871237375Z",
  "published": "2026-03-20T19:59:06.064Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4438.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-4438"
    },
    {
      "type": "REPORT",
      "url": "https://sourceware.org/bugzilla/show_bug.cgi?id=34015"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "gethostbyaddr and gethostbyaddr_r return invalid DNS hostnames"
}